In a communications system, to improve electric energy utilization, power management needs to be performed on a communication power supply in the communications system, to effectively distribute electric energy of the communication power supply to different loads in the communications system. When power management is performed, different loads may be powered on/off to allocate electric energy to the different loads. The different loads may be powered on/off by using a power-on/off drive circuit. That the different loads are powered on/off means that the different loads are powered on or powered off, that the loads are powered on means that power is supplied to the loads, and that the loads are powered off means that power supply to the loads is disabled.
Currently, a power-on/off drive circuit is provided. As shown in FIG. 1, the power-on/off drive circuit includes a load 1, a contactor 2, a relay 3, a relay drive circuit 4, a metal oxide semiconductor (Metal Oxide Semiconductor, MOS for short) transistor 5, and a MOS transistor drive circuit 6. One end of the load 1 is connected to a positive electrode of an external power supply, the other end of the load 1 is connected to a normally closed contact 2a of the contactor 2, and a normally open contact 2b of the contactor 2 is connected to a negative electrode of the external power supply. One end of a coil in the contactor 2 is connected to the positive electrode of the external power supply, and the other end of the coil in the contactor 2 is connected to a normally closed contact 3a of the relay 3. The relay 3 is connected in series to the MOS transistor 5, and a normally open contact 3b of the relay 3 is connected to a drain d of the MOS transistor 5. The relay drive circuit 4 is connected in parallel between two ends of a coil in the relay 3, the MOS transistor drive circuit 6 is connected in parallel between a gate g and a source s of the MOS transistor 5, and the source s of the MOS transistor 5 is connected to the negative electrode of the external power supply. In addition, when power-on/off driving is performed by using the power-on/off drive circuit, the relay drive circuit 4 controls closing or opening of the relay 3, and the MOS transistor drive circuit 6 controls turning on or off of the MOS transistor 5, so as to control closing or opening of the contactor 2, to power on or power off the load 1.
In a process of implementing the present invention, the inventor finds that the prior art has at least the following problem: Because the contactor 2 has a relatively large volume, and the relay 3 and the MOS transistor 5 need to be controlled by different drive circuits, an entire volume of the power-on/off drive circuit is relatively large.